For example, conventional methods of watching a stereoscopic image using a display, e.g., a liquid crystal display include the configuration shown in FIG. 5. In this case, for example, stereoscopic images for a right eye and a left eye are alternately displayed on each horizontal line on a display screen 1 of a liquid crystal display. A unidirectional linear polarizing plate 2 (which is directed rightward and upward in the figure) is applied to the entire surface of the display screen 1. Further, ½-wave plates 3, 3, . . . having the function of rotating a polarization angle 90 deg. are disposed on every other horizontal line, e.g., on all horizontal lines in even-numbered places, on the surface of the linear polarizing plate 2. Therefore, polarizing plates whose polarization angles are orthogonal to each other are consequently provided on respective horizontal lines in the form of a reed screen, as illustrated.
A viewer wears polarization glasses 4 having a polarization angle that matches each horizontal line. The polarization glasses 4 are constituted by a glass 4R for a right eye having a rightward and upward polarization angle and a glass 4L for a left eye having a leftward and upward polarization angle. Therefore, an image for a right eye and an image for a left eye respectively enter the right eye and left eye of the viewer independently of each other. That is, the image for a left eye on the even-numbered lines whose polarization angle is rotated 90 deg. leftward and upward by the ½-wave plates 3, 3, . . . can not be seen through the right eye glass 4R having the polarization angle directed upward to the right in the figure, and only the image for a right eye on the odd-numbered lines having a matching polarization angle can be seen.
On the contrary, the image for a left eye on the even-numbered lines whose polarization angle is rotated 90 deg. leftward and upward by the ½-wave plates 3, 3, . . . can been seen through the glass 4L for a left eye having a leftward and upward polarization angle in the figure, although the image for a right eye on the odd-numbered lines whose polarization angle is orthogonal to the same can not be seen.
No problem occurs with said glass 4L for a left eye because the image for a right eye is completely cut-off because of the polarization angle of said unidirectional linear polarizing plate 2. At the glass 4R for a right eye, however, since the ½-wave plates 3, 3, . . . for rotating the rightward and upward polarization angle have wavelength dependence (the rotating angle depends on wavelengths), it is not possible to accurately rotate visible light 90 deg. in the entire region thereof. As a result, the image for a left eye that is unnecessary cannot be completely cut off, which has resulted in partial leakage of the image for a left eye to cause crosstalk.